<template>
  <div class="app-container">
    <h2 style="text-align: center;">发布新课程</h2>
    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="最终发布"/>
    </el-steps>
    <el-form label-width="120px">
        <el-form-item label="课程标题">
            <el-input v-model="course.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
        </el-form-item>
        <!-- 所属分类 -->
        <el-form-item label="课程分类">
            <el-select
                v-model="course.subjectParentId"
                placeholder="一级分类" @change="subjectLevelOneChanged">
                <el-option
                    v-for="subject in subjectOneList"
                    :key="subject.id"
                    :label="subject.title"
                    :value="subject.id"/>
            </el-select>
            <!-- 二级分类 -->
            <el-select v-model="course.subjectId" placeholder="二级分类" @change="handleChange">
                <el-option
                    v-for="subject in subjectTwoList"
                    :key="subject.id"
                    :label="subject.title"
                    :value="subject.id"/>
            </el-select>
        </el-form-item>
        <!-- 课程讲师 -->
        <el-form-item label="课程讲师">
        <el-select
            v-model="course.teacherId"
            placeholder="请选择">
            <el-option
                v-for="teacher in teacherList"
                :key="teacher.id"
                :label="teacher.name"
                :value="teacher.id"/>
        </el-select>
        </el-form-item>
        <el-form-item label="总课时">
            <el-input-number :min="0" v-model="course.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
        </el-form-item>
        <!-- 课程简介 -->
        <el-form-item label="课程简介">
            <tinymce :height="300" v-model="course.description"/>
        </el-form-item>
        <!-- 课程封面-->
        <el-form-item label="课程封面">
            <el-upload
                :show-file-list="false"
                :on-success="handleAvatarSuccess"
                :before-upload="beforeAvatarUpload"
                :action="BASE_API+'/ossservice/upload'"
                class="avatar-uploader">
                <img :src="course.cover">
            </el-upload>
        </el-form-item>
        <el-form-item label="课程价格">
            <el-input-number :min="0" v-model="course.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
        </el-form-item>
        <el-form-item>
            <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
        </el-form-item>
        </el-form>
  </div>
</template>
<script>
import course from '@/api/edu/course'
import subject from '@/api/edu/subject'
import Tinymce from '@/components/Tinymce'
export default {
    components: { Tinymce },
    data() {
        return {
            saveBtnDisabled: false,
            course: {
                cover: '/static/01.jpg'
            },
            BASE_API: process.env.BASE_API, // 接口API地址
            teacherList: [],//封装所有的讲师
            subjectOneList: [],//一级分类
            subjectTwoList: [],//二级分类
            courseId: ''
        }   
    },
    created() {
        //回显课程基本信息
        this.init()
    },
    watch: { // 监听
        $route(to, from) { // 路由发生变化，方法就会执行
            this.init()
        }
    },
    methods:{
        init() {
            if (this.$route.params && this.$route.params.id) {
                this.courseId = this.$route.params.id
                this.getCourseById()
            } else {
                //初始化所有讲师
                this.getTeacherList()
                //初始化一级分类
                this.getOneSubject()
                this.course = {
                    cover: '/static/01.jpg'
                }
            }
        },
        //上传封面成功调用的方法
        handleAvatarSuccess(res, file) {
            this.course.cover = res.data.url
        },
        //上传之前调用的方法
        beforeAvatarUpload(file) {
            const isJPG = file.type === 'image/jpeg'
            const isLt2M = file.size / 1024 / 1024 < 2

            if (!isJPG) {
                this.$message.error('上传头像图片只能是 JPG 格式!')
            }
            if (!isLt2M) {
                this.$message.error('上传头像图片大小不能超过 2MB!')
            }
            return isJPG && isLt2M
        },
        //点击某个一级分类，触发change，显示对应二级分类
        subjectLevelOneChanged(value) {
            //value就是一级分类id值
            //遍历所有的分类，包含一级和二级
            for(var i=0;i<this.subjectOneList.length;i++) {
                //每个一级分类
                var oneSubject = this.subjectOneList[i]
                //判断：所有一级分类id 和 点击一级分类id是否一样
                if(value === oneSubject.id) {
                    //从一级分类获取里面所有的二级分类
                    this.subjectTwoList = oneSubject.children
                    //把二级分类id值清空
                    this.course.subjectId = ''
                }
            }
        },
        //查询所有的一级分类
        getOneSubject() {
            subject.getSubjectList()
                .then(response => {
                    this.subjectOneList = response.data.list
                })
        },
        //查询所有的讲师
        getTeacherList() {
            course.getTeacherList()
                .then(response => {
                    this.teacherList = response.data.items
                })
        },
        saveOrUpdate() {
            if (!this.course.id) {
                this.saveCourse()
            } else {
                this.updateCourse()
            }
        },
        saveCourse() {
            course.addCourse(this.course)
                .then(response => {
                    //提示
                    this.$message({
                        type: 'success',
                        message: '添加课程信息成功!'
                    });
                    //跳转到第二步
                    this.$router.push({path:'/course/chapter/' + response.data.courseId})
                })
        },
        updateCourse() {
            course.updateCourse(this.course)
                .then(response => {
                    //提示
                    this.$message({
                        type: 'success',
                        message: '修改课程信息成功!'
                    });
                    //跳转到第二步
                    this.$router.push({path:'/course/chapter/' + this.courseId})
                })
        },
        // 解决下拉组件不显示值的bug，利用@change事件绑定函数重新加载一下组件即可
        handleChange() {
            this.$forceUpdate()
        },
        getCourseById() {
            course.getCourseById(this.courseId).then(response => {
                this.course = response.data.courseVo
                subject.getSubjectList().then(response => {
                    this.subjectOneList = response.data.list
                    for (var i = 0; i < this.subjectOneList.length; i++) {
                        var oneSubject = this.subjectOneList[i]
                        if (this.course.subjectParentId === oneSubject.id) {
                            this.subjectTwoList = oneSubject.children
                        }
                    }
                })
                //初始化所有讲师
                this.getTeacherList()
            })
        }
    }
}
</script>
<style scoped>
.tinymce-container {
    line-height: 29px;
}
</style>
